Supplementary Material for: Altruistic Behavior Depending on Opponents’ Body Weight: An Experimental Approach

Background: Obesity is a worldwide public health issue, not only because it is associated with numerous comorbid diseases but also because of its impact on the social level. This study aims to investigate (a) whether altruistic behavior differs between people with obesity and people who are not obese, (b) altruistic behavior toward people who are obese, in particular, women who are obese, and (c) implicit and explicit attitudes toward people with obesity as predictors for divergent altruistic behavior. Methods: An experimental approach called the dictator game was applied. In total, 168 participants of normal weight were asked to divide a monetary reward between themselves and two opponents, one person who was obese and one with normal weight. In addition, participants’ implicit and explicit attitudes toward people with obesity as well as other sociodemographic data were assessed. Results: We found that altruistic behavior did not differ between obese and nonobese opponents (t(166) = –0.57, p = 0.71), nor did we find less altruistic attitudes toward women with obesity (t(85) = –0.03, p = 0.39). Linear regression models show less altruistic behavior among people with stronger explicit antifat attitudes (p = 0.015). However, although we found that participants held implicit attitudes toward people with obesity, these attitudes did not predict altruistic behavior toward people with obesity. Conclusion: Although numerous studies reported discrimination toward people with obesity in several areas of life, we did not find discrimination in form of less altruistic behavior toward people with obesity. Moreover, although we found implicit antifat attitudes among the participants, these attitudes did not predict altruistic behavior toward people of divergent weight groups. Therefore, future research should investigate more intensively the diverse facets of discrimination toward people with obesity, if and to what extent implicit antifat attitudes have a quantifiable impact on the stigmatization and or discrimination process, and the hypotheses in a more hidden way, since manipulation check revealed that the majority of participants anticipated the underlying idea of the dictator game.